<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<!--1.行内引入-->
<bottom onclick="alert('请先登录！')">点击即玩</bottom>
<bottom onclick="console.log('行内引入')">点击即玩2</bottom>
<!--2.内部引入-->
<h2 id="aaa">我是大标题</h2>
<script>
    console.log('行内引入');
    console.log(aaa);
</script>
<!--3.外部引入-->
<script src="外部引入.js">

</script>
</body>
</html>